Study On The Apoptosis And It's Pathway During Implantation In Yaks

15 female yaks were slaughtered in the 16th, 18th, 20th, 22th and 24th day of early pregnancy and the uteruses were collected in present study. Firstly, we observed the changes of endometrium epithelium and trophoblast cells during implantation by microscopy, scanning electron microscope and transimission electron microscopy as well as the adhesion of epithelia and trophoblast cells. Secondly, We investigated the apoptosis of endometrium cells and trophoblast cells by paraffin wax embedded for HE stained, DAPI stained, DNA in situ end labeling(TUNEL). The proliferation potential of the cells also been investigated by the expression characteristic of Ki-67 protein. Lastly, In order to clarify the pathway of apoptosis in yak uterine epithelium and trophoblast during implantaton, we have investigated different proteins such as TNFalpha, TRADD, Fas, Fas ligand, Bax and Bcl2 as well as caspase-9 and caspase-3 using immunohistochemistry. The results showed that: (1) the time of embryo implantation in yak was from 17 or 18th to 24th day of early pregnancy. The trophoblast cells orientated in apposite place of endometrium epithelium and attached with it, whilst a few of TGC invaded into lumen epithelium of endometriums, this is the symbol of implantation in yaks. In each day of early pregnancy, a lot of glycogen granules presented in the apical of epithelia cells and dissfused into the trophoblast cells. The junction between epithelia cells and tropboblast cells mainly is microvillus interdigitation, but sometimes there had tight junction and desmosome. About the source of multinuclear cells in the epithelia, at least partly came from the amalgamation of tropboblast giant cells with epithelia cells due to the phenomenon of the cell membrane disappear in the junction of epithelium and trophoblast cells. (2) The cells were apoptosis during embryo implantation drastically. Apoptosis cells showed condense chromatin or the formation of apoptosis body and been deeply dyed by HE stain. At the same time, the nucleus showed highly blue fluorescence by DAPI stain as well as the high green fluorescence by TUNEL. In the beginning of implantation, the characteristic of epithelia cell and tropboblast cell apoptosis was the condensing of nucleus, but in the late of implantation, there have of a lot of apoptosis body appear around the apoptosis cells. Furthermore, the apoptosis rate of endometrium cells was lower in 16th day of early pregnancy, increased in the 18th and achieved peak in the 20th (14.75%, 25.52% and 27.40%, respectively).But in the trophoblast cells, the peak appeared in the 18th of early pregnancy and decreased in the following days. Ki-67 protein could express in all stage of uterus epithelia and trophoblast, but the changes pattern in epithelia and trophoblast is different during implantation. In the epithelia, the rate of Ki-67 protein positive cells is 42.25% in 16th of pregnancy, and achieved peak in the 18th (57.75%), but decreased in the follow day of pregnancy. But in the trophoblast, there was not an obvious change. (3) The Fas and Fas ligand protein coexpressed in the epithelia and trophoblast as well as in the lymphocyte cells, indicated that the Fas and Fas ligand was concerned with the pregnancy immune response of...